Deprecated projection keyword in simple_plotly

[KS-HTK]

While reviewing Issues/1785 I discovered some deprecated and some complicated code.

Added deprecations for the projection keyword as geojson is always WGS84.

See PR #2470 for the removal of the deprecation.

[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 10 lines in your changes missing coverage. Please review.

Project coverage is 76.27%. Comparing base (37db174) to head (d1247ee).

Files with missing lines	Patch %	Lines
pandapower/plotting/plotly/mapbox_plot.py	28.57%	5 Missing ⚠️
pandapower/plotting/plotly/simple_plotly.py	85.18%	4 Missing ⚠️
pandapower/plotting/plotly/traces.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2469   +/-   ##
========================================
  Coverage    76.27%   76.27%           
========================================
  Files          282      282           
  Lines        32944    32953    +9     
========================================
+ Hits         25127    25134    +7     
- Misses        7817     7819    +2     

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